Objective To identify the characteristics of pneumoconiosis incidents and assess the dose-response relationship between cumulative dust dose and the incidence risk of pneumoconiosis through a dust-exposed worker cohort in a coal mine in Tangshan.
Methods All workers exposed to dust during 1970 to 2010 in the coal mine were enrolled as study subjects. Life-table method was used to analyze the cumulative dust exposure dose and cumulative incidence. Age of onset, years of dust exposure, and latency period of patients with coal miner's pneumoconiosis (CMP) were analyzed by one-way ANOVA. The incidence rates were analyzed by the χ2 test, and the cumulative incidence rates by Log-Rank test.
Results There were 17 023 coal mine workers meeting the enrollment requirements, including 838 CWP patients with an incidence rate of 4.92%. The incidence rates of tunneling, mixing, mining, and assistant workers were 17.91%, 11.35%, 8.74%, and 0.81%, respectively (χ2=1 168.08, P<0.001). The cumulative incidence rate was 49.79% for tunneling workers in the 1 700 mg/(m3& #183;years) group, 35.92% for the mining workers in the 1 800-mg/(m3& #183;years) group, 38.01% for the mixing workers in the 1 800-mg/(m3& #183;years) group, and 3.69% for the assistant workers in the 16-mg/(m3& #183;years) group.
Conclusion With the cumulative dust exposure dose increasing, the cumulative incidence rates of selected occupational categories increase. Within a certain range of cumulative dust exposure dose, the cumulative incidence rapidly grows, and the lower limit value of the range is identified as 900 mg/(m3& #183;years) for tunneling workers, 1 200 mg/(m3& #183;years) for mining workers, and 1 000 mg/(m3& #183;years) for mixing workers. These findings are of significant reference value.
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